In the three and a half year period beginning October, 1949, about 500 patients were treated by rotational and multiportal methods with supervoltage roentgen rays produced at two million volts. Most of these patients had advanced malignant disease. It has become evident that the patient treated with 2 million volt radiation is usually able to accept tissue doses in the 6,000 r to 8,000 r range delivered in 35 treatment days or 7 elapsed weeks and that larger fields that include adjacent regions of lymphatic spread can be included in such treatment. Radiation sickness is markedly less than would be obtained with smaller doses of conventional radiation, and, the skin reaction is often a threshold or moderate erythema when the skin is included in the region of treatment. Moist skin reactions may be encountered in special situations such as irradiation of the folds of the skin or when the x-ray